Influence of preparation methods in the structure and properties of Fe2O3/g-C3N4 composite catalysts

Abstract

The control of performance-oriented materials structure will be limited by the preparation of materials, and the research on the correlation between the preparation methods and the target structure will be an interesting direction. In this paper, three kinds of precursor mixture of Fe2O3 and g-C3N4 (FeCl3/DCDA-1, 2, 3) were prepared by mechanical compounding and simple hydrothermal method respectively. After calcination under the same conditions, Fe2O3/g-C3N4 composite catalysts were prepared. The relationship between the structure of the precursor obtained by different preparation methods and the performance of the composite catalyst was studied by thermal decomposition kinetics. The results show that in the simple hydrothermal method, compared with FeCl3/DCDA-3 obtained by drying only the composite crystals precipitated in the mixed solution, the activation energy of FeCl3/DCDA-2 obtained by drying the mixed solution increases with the increase of conversion rate, and has a higher pre exponential factor A value. This may be due to the increasingly strong interaction between Fe(OH)3 and dicyandiamide in FeCl3/DCDA-2, which makes dicyandiamide difficult to be converted into melamine in the calcination process. As a result, the interface interaction between Fe2O3 and g-C3N4 in the composite catalyst becomes stronger, forming a strong Fe–N coordination bond and promoting the separation of electron holes. Fe2O3/g–C3N4–2 has the highest photocatalytic activity among the prepared photocatalysts. It can degrade 62.0% of methylene blue (MB) under visible light irradiation for 60 min, which is 2.32 times that of pure g-C3N4 (34.6%). In addition, under the same conditions, Fe2O3/g–C3N4–2 can degrade 7.72% of ciprofloxacin (CIP).